How to implement locks in MSSQL database?

Question

SQL

Good afternoon. I am writing an application in C# that works with a MSSQL database.
Faced the following problem. Let's admit the user through SELECT loads the data on record in the form for editing. Another user deletes this entry at the same time. Accordingly, the first user at the time of UPDATE will have an error. Or another case - if both users decide to open the same record for editing.
As before, I was not fond of such tasks, I want to know which way to google for the correct implementation of the database locking mechanism in applications.

Answer 1

You just have the wrong approach.
You don't need to lock the record, you need to check its version/existence when updating the data.
At your approach, one will block the record and leave for lunch, the work has stopped.

Answer 2

Maybe many will not support me. But my task was to unlock editing, while leaving viewing for the rest. Leaving the version check alone seemed not enough, but I was afraid to implement it through a transaction: it is not known how isolation will behave if it has not been used before.
The implementation was through three additional fields and a couple of procedures. Three is really redundant. Two would be enough. In general, a kind of bike.
Header fields:
And the blocking procedure itself:

ALTER PROCEDURE [dbo].[LockUnLockOrder]
  @HeadGUID uniqueidentifier, @UserGUID  uniqueidentifier, @Lock bit
  
AS
BEGIN
  -- SET NOCOUNT ON added to prevent extra result sets from
  -- interfering with SELECT statements.
  SET NOCOUNT ON;
  
  if @HeadGUID is null or @UserGUID is null or @Lock is null 
  begin
  raiserror('Процедура LockUnLockOrder: Неинициализированный параметр',16,1)
  return -1
  end
if V_ORDER.dbo.CheckEditStatus(@HeadGUID,@UserGUID) = 1
begin
  if 	@Lock = 1			
  UPDATE [V_ORDER].[dbo].[OrderHeader]
  SET isEdit = 1
    ,BeginEdit = getdate()
    ,UserEdit = @UserGUID
  WHERE GUID = @HeadGUID
  else 
  if 	@Lock = 0			
  UPDATE [V_ORDER].[dbo].[OrderHeader]
  SET isEdit = 0
    ,BeginEdit = null
    ,UserEdit = null 
  WHERE GUID = @HeadGUID
  return 1
end
else raiserror('Невозможно изменить статус заказа',16,1)
end

And the function of checking the possibility of editing. If the user opened an hour ago, and did not close, then permission to edit is issued.

-- =============================================
-- Author:		k1lex
-- Create date: 20160818
-- Description:	функция возвращает разрешение редактирования заказа. 1 - можно редактировать. 0 - нельзя
-- =============================================
ALTER FUNCTION [dbo].[CheckEditStatus]
(
  -- Add the parameters for the function here
  @HeadGUID uniqueidentifier, @UserGUID  uniqueidentifier
)
RETURNS bit
AS
BEGIN
DECLARE @bit BIT

IF (
    SELECT COUNT(*)
    FROM [V_ORDER].[dbo].[OrderHeader] O WITH (NOLOCK)
    WHERE O.GUID = @HeadGUID
      AND (ISNULL(O.IsReadOnly, 0) = 1 OR (O.userEdit != @UserGUID AND O.IsEdit = 1 AND DATEDIFF(HOUR, BeginEdit, GETDATE()) < 1)	
      and [Status]=1
      )
    ) = 0
  SET @bit = 1
ELSE
  SET @bit = 0

RETURN @bit
END

Also I will support Peter that check of date of the last change is necessary. Just in case someone opens it and remembers in three hours what they opened and edits what has already been edited.